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FAQ: Radiation Risk From Medical Imaging

What You Need to Know About Radiation Risks From CT, Other Scans

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What are the benefits of medical imaging procedures?

Medical imaging has vastly reduced the need for exploratory surgery and greatly improves the efficiency of many kinds of surgical procedures. These images have revolutionized the diagnosis of many diseases and conditions, have improved treatment planning, and save lives via image-guided therapies.

Even though the scans are expensive, they can reduce costs by making hospital stays shorter.

What are the risks of medical imaging procedures?

Even when done properly, medical imaging procedures can damage DNA and increase a person's lifetime risk of cancer.

In the U.S., a person has a one-in-five lifetime risk of cancer. Imaging can increase this risk.

For example, a 2009 study estimates that a CT coronary angiography given at age 40 will cause cancer in one in 270 women and in one in 600 men. The risk is about twice as high for a CT scan given at age 20 and about half as high for a CT scan given at age 60.

But scans aren't always given properly. Without taking the right precautions, a patient may be exposed to too much radiation, thereby increasing the risk without increasing the benefit.

Lack of standardization compounds the problem. For example, another 2009 study found that in the San Francisco Bay area alone, the dose of radiation given in the same kind of CT scan varied 13-fold between the highest and lowest dose given by different hospitals.

Moreover, doctors may prescribe scans that aren't medically justified. And since risk from radiation exposure accumulates over a lifetime, certain scans may not be appropriate for people who've already had a lot of scans.

Cancer isn't the only risk. Accidental exposures to high doses of radiation can cause burns and hair loss. Cataracts can develop in eyes directly exposed to radiation.

What is the FDA doing to reduce the risks of medical imaging?

The FDA's basic plan is twofold: make sure that every scan is medically justified and optimize the radiation dose a patient gets in each procedure.

To accomplish this, the FDA is launching three initiatives.

The first initiative will require the makers of CT and fluoroscope devices to incorporate safeguards into the design of their machines and to provide better training. Ideas include:

Requiring the devices to display, record, and report settings and radiation dose

Requiring the devices to alert users when the radiation dose exceeds the optimal dose for most patients